Combined recording and reproducing



July 26, 1949. s. A. SCHERBATSKOY 2,477,145

COMBINED RECORDING AND REPRODUCING Filed March 23, 1945 3 Sheets-Sheet 1 V IN V EN TOR.

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July26, 1949. s. A. SCHERBATSKOY 2,477,146

COMBINED RECORDING AND REPRODUCING Filed March 25, 1945 SSheetS-Sheet 2 QZEDOI ly 26, 1949. '5. A. SHERBATSKOY 2 477,146

COMBINED RECORDING AND REPRODUCING Filed March 23, 1945 3 Sheets-Sheet 3 iatented July 26, 1949 UNITED STATES PATENT OFFICE 2,477,146 COMBINED RECORDING AND REPRODUCING Serge A. Scherbatskoy, Tulsa, Okla. Application March 23, 1945, Serial No. 584,427

. 13 Claims.

My invention relates to sound recording and reproducing systems and more particularly to magnetic recorders and reproducers known as telegraphones in which, as is well known, the signals are recorded by varying the magnetic condition of a moving magnetic member and are reproduced by causing such a magnetized memher to vary the induction in a suitable translatin'g device.

The object of my invention is to provide a novel method and apparatus of this kind and in gen era] to improve the operation of such a recording and reproducing system.

While magnetic recorders and reproducers are old and well known, they have never been used commercially to an extent comparable to the use of phonographs or film recording. There are a number of reasons for this, the more important or which are probably due to the fact that satisfactory quality of reproduction and satisfactory length of duration of the recorded program was possible only with quite voluminous apparatus using a large amount of magnetic wire and tape which occupied considerable storage space compared. to other methods of recording such as film or phonograph. disc.

In accordance with the general features of this invention. certain engineering requirements are necessary regarding the size and general arrangement of the elements used with particular ref= erence to the size of the wire. It is required that the wire be sufllciently large to provide at each instant a magnetic moment thatis capable of overriding the spurious magnetic moments generated by a stray extraneous field and that is sufliciently large so that its statistical fluctuations are small in comparison. It has been demonstrated that these requirements can be met by extremely-thin wire of the order of of an inch thick and it has been demonstrated that the use of suchiwire ofiers numerous important advantages, the main one of which is compactness of the storing mechanism and consequent adaptability of this system to the recording of long continuous messages. It has been demonstrated thatthe limit to. the thinness of the wire used is not caused by electric or magnetic considerations, but is due to the mechanical difficulties involved ,in the handling and threading of the extremely thin wire. I

An important feature of my invention consists in providing a removable and'compact cartridge type container which will include the magnetic wire in combination with a winding mechanism and the element forimpres'sing a magnetic field upon the wire. I propose to use wire of extremely small diameter and to provide a container that is dust tight and permanently enclosed. The wire contained in it is intended to be used over and over again without removing the wire from the container and without ever rethreading the wire through the recording head and the erasing head. The advantage of this arrangement is that an extremely long message can be recorded and stored within a single magazine having relatively small dimensions. For example, in a magazine of 3" by 7" by 1" dimensions, it is possible by using the principle of my invention to record a message lasting one-half hour. This is more 7 economical of space than any prior arrangement of magnetic recording and actually compares very favorably with the most economical recording means, such as recording on film or recording on a phonograph disc.

In particular, this invention deals with a mechanism for driving the wire at a constant lineal speed and with a mechanism for storing long length of the wire on a spool. In the past great dimculty was encountered in providing a mechanism for accomplishing the above ends which was also adaptable to frequent starts, stops and reversals. The usual mechanism provided in the past consisted of two spools, the one driven by a motor and the other provided with a brake. in a mechanism of this sort the wire was unreeled from the spool provided with the brake (which we can refer to as spool A) past the recording or reproducing head and then was reeled onto the spool driven by the motor (spool B). When it became desirable to stop and reverse (as, for example, in a dictaphone where it is frequently desired to listen to passages that have Just been dictated) it was necessary to remove the braking mechanism from spool A and to engage this spool with the motor driven mechanism and at the same time to provide a. braking mechanism for spool B. This necessarily required a fairly complicated and cumbersomemechanical arrangement which usually employed disengaging clutches and the like. In general, it hasbeen found that mechanisms of this sort were not conveniently adaptable to uses where frequent stopping and reversing were required. I

In a pending application of mine, entitle Combined recorder and reproducer, filed February 18, 1943, Serial No..476,368, a novel system of magnetic recording is described and claimed. This application is also directed to a new system of magnetic recording, and to a novel combination of elements employed th'erewith.

It is an object of the present invention to provide a novel apparatus for magnetic recording and reproduction.

It is another object of my invention to provide a novel means for driving the wire where almost instantaneous reversals are possible without any mechanical components whatsoever. All that is required is a reversible motor.

Whereas, in the usual arrangement the full spool is usually on one shaft and the empty spool on a separate shaft and the wire is going from one spool to another, in my arrangement the empty and full spools are on the same shaft mounted coaxlally with the wire passing over a drive pulley which I shall hereinafter refer to as the capstan.

It is another object of my invention to provide a magnetic recorder and reproducer a removable and compact cartridge type container which will include the magnetic wire in combination with a winding mechanism and an element for impressing a magnetic field upon the wire.

It is another object of my invention to provide a-mechanism for driving the wire at a constant lineal speed.

It is another object of my invention to provide at any instant a visual indication of the amount of the wire that has already received the magnetic impressions of the signals to be recorded.

It is another object of my invention to provide a mechanism for automatically stopping the drive pulley when the winding or the unwinding process has been completed.

Further objects of my invention will become apparent from the following description of my invention taken in connection with the accompanying drawings, in which:

Fig. 1 shows an exterior view of the speech recording and reproducing device.

. Fig. 2 shows an exterior view of the removable magazine which constitutes one of the elements of the device illustrated in Fig. 1.

Fig. 3 shows diagrammatically the mechanism for driving the wire and the general wiring diagram of the magnetic recorder and reproducer.

Fig. 4a. and Fig. 4b show two different views of the removable cartridge,

Fig. 5 shows diagrammatically certain relationships involving the inclination of the shaft of the storage spools with respect to the shaft of the drive pulley.

Fig. 6 shows a mechanism for stopping the drive pulley when the magnetic wire has completed its travel.

Referring now more particularly to the drawings, Fig. 1 illustrates the general exterior view of the magnetic recorder and reproducer constructed in accordance with the teachings of the present invention. All the essential component parts of my recorder and reproducer with the exception of the source of power are contained in the single unit illustrated. This unit includes a housing member or masterunit'lll and an element ll, hereafter designated as removable magazine," said removable magazine containing the magnetic wire in combination with a winding mechanism. and elements for recording, reproducing, or erasing the magnetic field from the wire. The housing member contains all the remaining components of the magnetic recorder and reproducer, such as a driving means, a loudspeaker, electrical circuits for connecting the loud-speaker to said elements, etc. The housing it is provided with a base l2, a top wall I3,

and a front panel ll. The-front panel M in- '4 cludesa loud-speaker II and various switches used in controlling the apparatus.

Fig. 2 represents a view of the removable magazine showing plugs lulu, I620, Ma, Ma and a clutch member 26. The plugs and the clutch member are arranged to make the proper electrical and mechanical connection required between the removable magazine and the master unit shown on Fig. 1 and are arranged to couple the two units with the required mechanical rigidity so that when in place, the magazine ll becomes an integral part of the whole mechanism. The arrangement illustrated in Fig. 3 shows again the removable magazine ll, plugs lllla, l62a, 84a, am, and the clutch member 20. The removable magazine contains two spools 25 and 26 which are provided with a record carrier, 1. e., a steel wire or tape 21, for example, in such a manner that this wire or the like can be wound from one spool onto the other and then be rewound, as is customary with telegraphones and like devices. The spools 25, 26 are adapted to be driven in either direction by a drive pulley or a capstan 28 mounted upon a shaft 29. Consequently, the wire is wound back and forth from one reel to the other depending upon the desired direction of operation. If a recording is to be made, the wire is wound of! the spool 25 and on to spool 26. The same direction is used for reproducing a. recording on the wire. Between the making of a recording, and the repro duction of that recording, the wire may be rewound on spool 25 and unwound from spool 26 to the extent of the length of the recording, and then the apparatus may be started again in the forward direction for purposes of reproduction.

Assuming that the .wire is being wound from spool 25 to spool 26 in the direction of recording and reproduction, the wire passes through an erasing or demagnetizing head 30 and through a magnetic recording head 3!; then through the capstan 28 and onto the spool 26.

If a recording is already on the wire as it travels in the above manner during the making of a new recording, the previous recording will be erased by the demagnetizing head 30, and the wire will be magnetized in accordance with the new recording as it passes through the recording head 3|. If a reproduction is being made as the wire travels from reel 25 to reel 26, the demagnetizing head 36 is cut out of service, and the recording may be audiblyreproduced.

The shaft 29 carries a clutch member 20. When the removable magazine I I is inserted into the main housing It, the clutch member 20 becomes engaged into the shaft 60 of the motor 32, said motor being located in the main housing outside of the removable magazine H. The motor 32 may be of the D. C. type and is provided with an armature 33 and an excitation winding 34. The armature 33 is supplied with electrical energy from a, battery 35 and the excitation winding 34 is supplied with electrical energy from a battery 36 through a reversing switch 31. By means of the reversing switch 31 the motor 32 is arranged to rotate at will in the normal or in the reverse direction. When it is desired to record speech upon the wire 21, or to reproduce speech from the wire 21, the motor 32 is made to rotate in the normal direction and causes the wire. to be unwound from the reel 25 and wound upon thereel 26. When, however, it is desired to rewind the wire upon the spool 25 and to unwind from the spool 26. the motor 32 is arranged to rotate in the reverse direction.

The spools 25 and 28 are free to rotate on the shaft 45 which serves merely as a. support for the spools. Shaft 45 is not driven in. any manner but is stationary and the spools are free to rotate on this shaft. Spool 25 is joined to spool 26 through a helical spring 50. The purpose of the spring 50 is to provide tension to wire 21. In operation the spring 50 is winding "up so as to provide torsion between spools 25 and 26. The direction of the torsion is such as to tend to wind the wire onto spools 25 and 28; The direction of torque exerted by the spring is shown by the arrows C and D. It can be seen therefore that the spring 50 keeps the wire 21 taut and fairly pressed against the capstan 28. Therefore. when the motor 32 rotates, it turns the capstan 28 and the wire is driven. It can be seen that as the wire is driven, it winds onto one of the spools and off theother spool. The action actually is as follows: Assume that the motor 32 drives the capstan 28 in the direction indicated'by the arrow E. The wire will be pulled off of spool 25 asshown by the arrow F, and the wire will.

ameters'of spools 25. and 26 can be considered.

equal and therefore the angular velocity of the spools will also be equal; Consequently the springin is in effect being wound up" and unwound", at the same rate; i w en; the lengths of the wire become appreciablathe "fullf' spool will have a diameter-somewhat larger than the v I "emptyispool and, 'theref ore,' there is a tendency to wind theyspring 50. .It' is necessary'therefore master unit I0, numerals IOIa, IOIb designate the plugs used to connect and disconnect the erasing coil 30 with the apparatus located within the master unit I0, and numerals 84a, 8% and 8Ia, 8|b designate plugs to connect the circuit for supplying the current to the armature of the motor 32 and arranged in such a manner that this supply stops when the winding or the unwinding process has been completed. Another important part of the system is the switch arrangement which consists of the double pole switches I03, I04, I05, I06 and I07. All of these switches are arranged to be controlled by a single lever so that when the lever is in the "record" position the switches I03 to I01 are all in the up position as indicated by the solid arrows in Fig. 3. When this switch is placed into the reproduce position all the switches are in the down position which corresponds to the dotted lines shown on Fig.8.- When this switch is either in the record or freproduce position. the corresponding reversing switch 31 is in such a position as to cause the motor '32 to unwind the wire from the spool 25 and to wind the wire upon the spool 28.. The alternate position of the reversing switch 31 causes the rewinding of the spools and then the switching arrangement for actuating the recording or reproducing process is disconnected; Assume now that the switching arrangement in the up position indicated by the solid arrows and with further reference to Fig. 3 the operation is as follows:

- when long lengths of wire are. being handled to provide a spring 50 which can store many revolutions. .Ffurthermore. it .is clear that in order to'provide uniform winding'of the wire on the spools it is necessary to provide guides that will layer wind the wire uniformly.

As shown'in Fig. 3, thewire 21 is arranged to pass from the spool 25 to the capstan 28 through the erasing head 30 and through the recording head 3|. The erasing head 30 consists essentially of a coil of wire wound on an axis coincident with the axis of a small cylindrical hole 5| through which the wire passes. The winding of the erasing head is wound on a bobbin which is preferably made of Bakelite or wood or some currents that are representativeof the sound' waves. Usually, when aloud-speaker is operated other non-magneticgmaterial. The recording a head consists of. a high. permeability core 52 which is made of a series ofthin laminations insulated one from theoth'er, The winding; of the recording head is wound around an axis that coincides with the position occupied by the wire 21 as it passes through the hole 53 provided in the high permeability core 52.

An important part ofv the arrangement illustrated'in Fig. 3- is the provision of the plugs which are arranged to connectfand disconnect -the apparatus housed within themagazine |I a from the apparatus housing within'the master unit I0. The plugs designated by'the numerals |0|d, I02a, 84a, and-:O'la are securely connected to the wall of 'theremovablemagazine. II and are insertable into the.correspond ing plugs of the housing I0 that are designated by the numerals I0|b, |02b, 84b, 8|b, respectively. Nu-

merals I02a, |02b designate plugs which are arranged to connect and disconnect the recording head 3| and the apparatus located within the I or asa microphone. When it operates as a microphone the sound waves impinge upon the diaphragmand cause. motions-in theelectrodynamic transducing' mechanism'which generate electrical in this manner, i. e., as a microphone, itsfrequency characteristic is unsatisfactory and requires equalization in, order to improve the quality of the reproduced sound. Therefore, in Fig. 3 the speech currents generated by the loudspeaker I5 are impressed through the switch I03 on an equalizer I09 which serves to improve the quality of reproduction ina manner that'is well known in the art. After passing through the equalizer the speech currents are impressed through the switch I04 on to the amplifier H0. The output of the amplifier is impressed through the switches I05 and I06 and therplugsl I021). I021: on to'the recording he'ad3 I. In the recording head alternating magnetic-fields are impressed upon the wire ll-which are a reasonably the recording head 3| it is demagnetized by passing through the demagnetizing coil 30. This de-- magnetizing coil is energized with a high frequency alternating current which is generated by the oscillator H4 and which is impressed on the demagnetizing coil through the-switch I01 and the plugs I0|b,-'|0|-a.- In the arrangement shown (switches in the up position) the wire 21 therefore is demagnetized first in'the coil 30 and then passes through the recording head 3| in which alternate magnetic field is generated which represents the speech;

Assume now that the switch is in the down position, i. e., the switches I03, I04, I05, I08, I01

aevaise occupy the position shown by the dotted lines on Fig. 3. This corresponds to the "reproduce condition and the operation of the circuit is as follows:

The oscillator I I4 is now disconnected from the erasing coil 30 and the erasing coil therefore is not energized and the wire in passing therethrough retains whatever magnetism that existed in it. The wire now passes through the recording head 3! which responds to the magnetic field generated by the wire and produces a-voltage across the winding of the recording head which is approximately proportional to the rate of change of the magnetic flux. The voltage is impressed across the plugs ill2a, i022 and through the switch 806 is impressed across the terminals of the equalizer I29. This equalizer serves essentially as an integrator, such an integrator has been previously described in U. S. Patent No. 2,099,536 and reference .is made thereto. The purpose of this integrator is to produce a voltage at its output which is substantially proportional to the integral of the input and consequently which is substantially proportional to the flux generated in the recordinghead 3! rather than to the rate of change of flux therein. The output of the equalizer I20 is impressed through the switch I04 onto the input of amplifier ill] and the output of the amplifier H is connected to the switch I05 and I03 onto the loud speaker l5 which is arranged to transduce the electric current into audible sound. The operation of the circuit therefore is such that the loud speaker 55 generates a sound which is substantially a facsimile of the magnetic flux generated in the recording I head 35.

. the wire over from a position which is substanbalance this tendency, the shaft 29 is inclined with respect to the shaft 55 by an angle a (as shown in Fig. 5), said angle being such that d tail (II- Then the frictional forces that are developed because of the pressure of the wire 2'! upon the periphery of the capstan 28 are largely tangential and there is no force tending to modify the inclination a between the shafts 29 and 55. It is therefore seen that since it is desired to carry tially in line with the other spool, an inclination between the axis of the capstan 28 and the axis of the spools 25, 26 is desirable.

The shaft 65 is siidably supported in bearings 2G8 and 269 so that the shaft bears against a cam mechanism and against cam sac. Cam m is arranged to rotate at an appropriate very low speed through .the gear train 2H. Cam m is arranged so as to shift the spools 25 and 26 as a unit back and forth as shown by arrow G. The purpose of this cyclic sliding is to provide a level wind. It can be seen that since the wire has to be wound in' a series of layers it is necessary to guide the wire with respect to the pulleys. Obviously, this can be achieved by allowing the wire to remain in a fixed position and move the pulleys instead. The wire 21, the erasing head 30 and the recording head 3i are not shown in Fig. 4a

' and Fig. 41).

Fig. 4a and Fig. 4b show two different views of g the removable magazine in a modified form. The removable magazine H is here arranged to be removed from or attached to the main housing of the magnetic recorder In by means of the screw arrangement which is actuated by handle 202. The spools that have been described previously are indicated by numerals 25 and 26. The helical spring which was referred to as numeral in Fig. 3 in this arrangement is inside the spools. The spools-25 and 26 are hollow and are arranged so as to house the helical spring inside their hollow spaces and is therefore not shown in Fig. 4a

and Fig. 4b. The action of the helical spring,

however, is identical to the action described in Fig. 3 and the spools 25 and 26 are arranged to exert torque one with respect to the other. The capstan is shown as numeral 28 and is mounted on shaft 29, while the spools 25 and 26 are mounted on the shaft 45. The axis of the shaft 29 is inclined with respect to the shaft 45 in order to facilitate the smooth level winding on the spools. This axial inclination is shown in Fig. 4b and can be understood better with reference to Fig. 5. Assume that the diameter of each spool is'D and its thickness is d and assume also that both spools are immediately adjacent one to the other. Let KL and MN represent two planes bisecting the spools 25, 26 which for the purpose of our discussion can be considered as the planes of the spools 25 and 26, respectively. It can be readily visualized that if the capstan 28 were parallel to the spools 25, 26 the magnetic wire frictionally engaged upon the periphery of the capstan would tend to incline the shaft 29 of the capstan with respect to the shaft 45 of the spools, and this tendency would be stronger if the thickness d of the spools is larger. In order to counter- It is important to point out that the mechanical arrangement for handling very long lengths (sometimes many miles) of extremely fine wire is of very great importance in magnetic recording. Dimculties have been encountered in the past in conventional arrangements employing brakes since most of these brakes use mechanical friction. It is well known that the friction coefficient between two solid bodies is an unreliable quantity which varies tremendously with the speed of motion and by slight impurities along the surfaces. Very small quantities of liquid such as oil or water produce changes, and, in magnetic recorders of the prior art, difflculty was encountered due to condensation of atmospheric.

moisture on the brake surfaces. Any substantial change in the coefiicient of friction would tend to rupture the wire. In the arrangement described in this invention the force of the wire is entirely determined by the properties of the helical spring so in connection with Fig. 3. The

tension on the wire, therefore, is not affected by any such variable influences as frictional coeflicients. Furthermore, when stopping, starting and reversing, no mechanical clutches and the like are engaged or disengaged, and this again obviates the possibility of any sudden forces being exerted on the wire. The external influence exerted on the wire is by means of the capstan. The motion of the wire when driven by the capstan is uniform and smooth because the diameter of the capstan is constant. In the prior arrangevantages just described the arrangement of this invention permits the employment of finer wire than was employed in any previous arrangeand not only have no ruptures occurred, but it v has turned out to be impossible to cause a break in the wire-by any external means.

Also connected to the shaft 29 of the capstan 28 is a counter mechanism l6 which indicates the length of a portion of the record medium 21 that has passed through therecording or reproducing head 3|. By means of such a counter mechanism the speaking person may be able to ascertain how longthe machine will still be able to record, that is, to ascertain the length of that piece of steel wire or tape which is still available for recording. With reference to this arrangementit can be pointed outjthe wire moves in strict'synchro- I ism with the capstan 28 and since the diameter oi-the capstan wheel is constant, the length of the wirethat has been wound bythe capstan is ri orously determinedbythe number of revlutions or the'.capstan shaft 29. The counter i6 provides thereiore anyaccurate indication of the length of wire thathas traversed through the recording or'reproducinghead.

J An important-reature of my'invention consists in the provision of means by'whichthe motor'32 automatically stops when the wire 2'! has reached v theend oi itstravelg Sucha situation may occur twicelifegat the end "ofthe] recording or reproducing-process, when-thespoOl-ZS is completely 4 j g unwound" and the spool 26 is fcompletely' wound, J -,.or at the end of therewihfdingprocess when the apparatus is run. 1baclqavar(is'. 'Under the latter condition-the p ol-12s is completely unwound, 5 andthe spool 251s completelywound. The gears ,ging ratioi-is 'snchf-that' under both conditions,- 1 if 'eg atthe end of thejrecording or: reproducing jfproces's, orat-the endof the rewinding process the revolution counteri indicates the digit zero on all its cylinders and, at this instantit is desired to stopthe motor 3 2. Iam accomplishing'the above-purpose bymaking the following provi- The revolution counter li -is of a conventional cylinders 16a, '16b,*--.1,6c, etc. The external surfaces of the cylinders are provided with a shecession or digits." The shaft 13 is coupled to the -wire'80, plugs 8la,

connection. .40

10 the end of the recording or reproducing process, or at the end of the rewinding process.

As shown in Fig. 3 and Fig. 6, the outer casing 10 of the revolution counter i8 is electrically connected by means of the wire 80 to a plug 8|a. When the casing ii enters into the housing ID, the plug 8|a becomes inserted into a plug 8"), said plug Bib being connected to ground. In the 'present description the ground indicates symbolically the outer metallic wall of the housing It]. Consequently, upon the insertion of the removable magazine ll into the housing ill, the walls .70 of the revolution counter I 6 are electrically connected to theouter metallic wall of the housing Ill.

The brush 18 is mechanically supported by means of the metallic spring I9 to the metallic spring holder 82. Furthermore, the brush 18 is electricallyconnected through the wire 83 to a plug 84a. When the casing Ii enters into the housing 10, the plug 84a becomes inserted into a plug 841'), said plug 84b being connected to one of the battery to the ground, 1. e.,,tothe outer metallic well of the housing III'.

' From inspection'of Fig. 3 and Fig. 6 it becomes apparent that whenever the winding or unwindingpro'cess of the spools 25', takes place and has .not reached its completion, the. armature '33 of the motor 32 is continuallyenergized by the battery, 35, since one terminal orthe armature is connected to thefbattery'directly and the. other terminal of the armature is connected to,- the battery through the plugs "84a, Mb, wire 83, brush '18, metallic digit elements, the body of the cylinder 16, the wall In of the revolution-counter,

' all) and through the ground Therefore, under these circumstances, the motor 32 is kept running and its direction is determined by the position "of the reversing switch 31. As soon, however, as the brush enters into contactwith the insulatordigit element representing numeral twoatthe end of the recording. reproducing or rewinding process, this connection is'autoirl'at'ically' interrupted and the motor 32 stops.

ydesign and as shownl in-Flg. 3and Fig. 6, it is I Iprovidedwith' a metallic casing 10 having a main shaft 13 and having'mounted thereon the counter I It is therefore apparent that I have provided a system for automatically stopping the motor 32 as soon as thewire '2'! has reached the end of its traveLthus preventing abreakage of the wire.

cylinder indicating the digit of the highest order I is provided-with a commutator arraingement and astationary metallic, brush I8 is arranged to press :against this cylinder funder the'action-off-tha .spring 19; onefend in; said springlbeing secured {to-an appropriate spring holdersl. All the digit .elern'entsj,onythefcylinder16a are metallic with -.the"exceptionto i thefdigit element-representing the inim efral.two. andfconsequently. they arein an electr'icalcontact;with the shaft '13 and with the wall I0. kTherdlgit'elemenir that represents the 'numeral' t wojis made 01' an insulatingma- --terial. The arrangement,""furthermore, is such that when the digitfaq is opposite the windowroi. thecounter, the'dig-itjls. opposite the brush, It *is apparentthat the insulating digit element rep resenting the digit two comes in front of the metallic brush "l8 only 'at two instances, 1. e. at

. It is apparentthat after the motor circuit is interrupted and the motor stopsv because of the .automaticmeans just described. it will bene'cessary to re-establish the motor-circuit momentarily in order to start itagain. It is necessary therefore toprovide a switch-that can be operated manually inform of a push button and which will bridge the insulating segment represented by the digit two on thecounter drum 16a.

manual switch is represented bythe nu- .meral 85 on Fig.-. 1, Fig. 3, and Fig. 6. The above described mechanism; be appreciated by those skilled in extremely compact and rugged equipment 'for recording and'reproduction of sound vibrations. It

' is essentially acombination or, two features, one

- of a removable magazine thatincludes the wire of which resides in the particular drive 11160118.-

nism herein disclosed, and the other'feature-consists inthe use or a single structural unit in form and spools and .the recording head, all'inclosed Y within a. single dust-tight case and provided with clutches connected to the spools and electrical plugs connected to the recording head. Because as will readily theart. is an accuse in the arrangement above described the recording head is inseparable from the wire, I have been able to provide a very small clearance between the size of the hole in the recording head and the size of the wire passing through it, and the complete shielding of the wire in the recording head in all regions except the region within the air gap.

While I have shown a particular embodiment of my invention, it will, of course, be understood that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

I claim: I

1. In a magnetic recorder and reproducer, two storage spools mounted on the same shaft in sideby-side relationship, a driving spool mounted on another shaft conveniently distant from said first shaft, a recording wire frictionally engaged with the periphery of said driving spool and adapted to be wound or unwound upon either of said storage spools, an elastic member wound around said first-named shaft between said two spools and connecting said two storage spools to exert a torque upon said storage spools whereby said wire is kept constantly taut and pressed against the periphery of said driving spool, a reversible motor drivably connected with said other shaft, and a control mechanism for causing said motor to rotate in a clockwise or anticlockwise direction for controlling the motion of the recording wire from one storage spool to the other storage spool or vice versa.

2. In a reeling system for a, reelable magnetic record, a plurality of reels mounted in side-byside relationship for independent rotation about a common axis, guide means spaced from said reels and over which said record is adapted to run from one reel to another, and spring means connecting said reels in torque transfer relation whereby said reelable record is kept constantly taut against said guide means regardless of variations in the effective diameters of said reels resulting from variations in the quantity of reelable record on said reels during said run.

3. In apparatus of the character described, a plurality of reels mounted in side-by-side relationship for independent rotation about a common axis, a magnetic-wire record secured at one end to one of said reels and at its opposite end to another of said reels whereby upon rotation of said reels in a common direction said wire will be wound on one reel while being unwound from the other, guide means spaced from said reels and around which said wire is adapted to run in its journey from one reel to the other,

a spiral spring wound about said common axis and connected adjacent to its opposite ends to respective ones of said reels whereby any slack in said wire is taken up and said wire is kept constantly taut against said guide means irrespective of the direction of rotation of said reels, and means adapted to rotate said reels in a selected common direction.

4. A telegraphone-record cartridge comprising a casing containing a hollow reel having an axis of rotation, a second hollow reel mounted for independent rotation about said axis adjacent to said first mentioned reel with the hollow portions of said reels arranged to form a chamber common to said reels, a flexible magnetic record secured at one end to one of said reels and at its opposite end to another of said reels whereby upon rotation of said reels in a common direction said record will be wound on one reel while being unwound from the other, guide means spaced from said reels and around which said wire is adapted to run in its journey from one reel to the other, and a spiral spring disposed about said axis within saidchamber and connected adjacent to one of its ends to one of said reels and adjacent to the other of its ends to the other of said reels for tensioning said record against said guide means regardless of variations in the effective diameters of said reels resulting from variations in the quantity of said flexible record on said reels during said run.

5. In a system for driving a reelable magnetic record, a pair of reels for holding said record and independently rotatable about a common axis of rotation, rotatable guide and drive means spaced radially from said axis of rotation and over which said record is adapted to run from one of said reels to the other, torque transfer means connecting said reels in torque transfer relationship to effect relative rotation between said reels in the proper direction to hold said record taut against said guide means as the effective diameters of said reels change during movement of said record from one reel to the other, means for rotating said guide and drive means at a substantially constant speed, and camming means driven by said last-named means in timed relationship with movement of said record for moving said reels longitudinally of said axis of rotation to effect level winding of said record on said other reel.

6. Magnetic recording and reproducing apparatus comprising a master unit provided with magnetic record drive means, a record cartridge detachably mountable upon said master unit and comprising a casing, a pair of reels mounted within said casing to hold a magnetic record and independently rotatable about a common axis of rotation, a rotatable guide and drive element mounted in said casing in radially spaced relationship to said axis of rotation and over which said record is adapted to run from one of said reels to the other, torque transfer means connecting said reels in torque transfer relationship to effect relative rotation between said reels in the proper direction to hold said record taut against said element as the efiective diameters of said reels change during movement of said record from said one reel to the other, means mounted in said casing and detachably engageable with said drive means to rotate said element at a substantially constant speed, camming means in said master unit driven by said drive means in timed relationship with movement of said record from said one reel to the other, and means including a shaft projecting through the wall of said casing to engage said camming means and rotatably supporting said reels for moving said reels longitudinally of said axis of rotation to effect level winding of said record on said other reel.

7. Magnetic recording and reproducing apparatus comprising a master unit provided with magnetic record drive means, a record cartridge detachably mounted upon said master unit and comprising a casing, a pair of rotatable reels mounted within said casing to hold a magnetic record, means disposed within said casing and including a part detachably engageable with said drive means for unreeling said record from one of said reels and reeling it up on the other reel, a cam and cam follower assembly forming a part 13 of the said master unit, said cam being driven by said drive means to produce reciprocating movement of said cam follower, and means within said casing actuated by said cam follower through an opening in said casing for producing relative movement between said record and said other reel to eifect level winding of said record on said other reel.

8. In-a reeling system for a reelable magnetic record, a pair of reels mounted in side-by-side relationship for independent rotation in either direction about a common axis, guide means spaced from said reels and over which said record is adapted to run from either of said reels to the other, and a multi-revolution spring disposed between and connecting said reels in torque transfer relation during a run of said record in either direction between said reels, whereby said record is kept constantly taut against said guide means regardless of variations in the eiiective diameters of said reels resulting from variations in the quantity of reelable record on said reels during said run.

9. In a reeling system for a reelable magnetic record, a pair of reels mounted in side-by-side relationship for independent rotation in either direction about a common axis, at least one of said reels having a recess therein opening toward the other reel, guide means spaced from said reels and over which said record is adapted to run from either of said reels to the Other, and a multi-revolution spring at least partially disposed in said recess and connecting said reels in torque transfer relation during a run of said record in either direction between said reels, whereby said record is kept constantly taut against said guide means regardless of variations in the effective diameters of said reels resulting from variations in the quantity of reelable record on said reels during said run.

10. In a system for driving a reelable magnetic record, a pair of reels for holding said record and independently rotatable about a common axis of rotation, guide means spaced from said axis of rotation and over which said record is adapted to run from one of said reels to the other, torque transfer means connecting said reels in torque transfer relationship to eilect relative rotation between said reels in the proper direction to hold said record taut against said guide means as the eflective diameters of said reels change during movement of said record from one reel to the other, means for moving said record between said reels, and means including a cam driven by said last-named means in timed relationship with movement of said record for moving said reels longitudinally of said axis of rotation to eil'ect level winding 01 said record on said other reel.

11. In apparatus of the character described, a plurality of reels mounted for independent rotation about a common axis, a magnetic-wire record secured at one end to one of said reels and at its opposite end to another of said reels whereby upon rotation of said reels in a common direction said wire will be wound on one reel while being unwound from the other. guide means spaced from said reels and around which said wire is adapted to run in its Journey from one reel to the other, a spiral spring wound about said common axis and connected adjacent to its opposite ends to respective of said reels whereby any slack in said wire is taken up and said wire is kept constantly taut against said guide means irrespective of the direction of rotation of said reels, and means adapted to rotate said reels in a selected common direction.

12. In apparatus of the character described, a hollow reel having an axis of rotation, a second hollow reel mounted for independent rotation about said axis adjacent to said first mentioned reel with the hollow portions of said reels arranged to form a chamber common to said reels, a flexible magnetic record secured at one end to one of said reels and at its opposite end to another of said reels whereby upon rotation of said reels in a common direction said record will be wound on one reel while being unwound from the other, guide means spaced from said reels and around which said wire is adapted to run in its Journey from one reel to the other, and a spiral spring disposed about said axis within said chamber and connected adjacent to one of its ends to one of said reels and adjacent to the other of its ends to the other of said reels for tensioning said record against said guide means regardless of variations in the eil'ective diameters of said reels resulting from variations in the quantity of said flexible record on said reels during said run.

13. In a reeling system for a reelable magnetic I record, a plurality of reels mounted for independent rotation about a common axis, guide means spaced from said reels and over which said record is adapted to run from one reel to another, and a spring directly connecting said reels whereby said reelable record is kept constantly taut against said guide means regardless of variations in the efiective diameters of said reels resulting from variations in the quantity or reelabl record on said reels during said run.

SERGE A. SCHERBATSKOY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 372,260 Griswold Oct. 25, 1887 789,336 Poulsen et a1. May 9, 1905 1,123,147 Sherman Dec. 29, 1914 1,718,355 Hutchison June 25, 1929 2,080,812 Fairbanks May 18, 1937 2,089,287 Molloy Aug. 10, 1937 2,304,913 Herzig Dec. 15, 1942 2,349,018 Tasker May 18, 1944 FOREIGN PATENTS Number Country Date 117,976 Austria June 10, 1930 313,672 I Great Britain June 20, 1929 585,406 Germany Oct. 3, 1933 641,843 Germany Rb. 15, 1937 

